Tyrphostins and other tyrosine kinase inhibitors

Deciphering the Knoevenagel condensation: towards a catalyst-free and water-mediated process

The Knoevenagel condensation constitutes one of the most well-studied and crucial transformations in organic chemistry, since it facilitates the synthesis of numerous valuable compounds. With the advent of green chemistry, several alternative protocols for the Knoevenagel reaction have been introduced and catalyst-free approaches to the Knoevenagel condensation have also been mentioned, however the harsh temperatures employed and the limited substrate scope restricted their application. Herein, we have performed an extensive study on the catalyst-free and water-mediated Knoevenagel reaction, with specific focus on optimising the green parameters and metrics of our methodology. Additionally, we directly compared our approach with previous catalyst-free methods, while providing a fast assembly of multiple compounds in parallel.

Unlocking the potential: unveiling tyrphostins with Michael-reactive cyanoacrylate motif as promising inhibitors of human 5-lipoxygenase

Human 5-lipoxygenase (5-LO) is the key enzyme in the biosynthesis of leukotrienes, mediators of the innate immune system that also play an important role in inflammatory diseases and cancer. In this study, we present compounds, containing a Michael-reactive cyanoacrylate moiety as potent inhibitors of 5-LO. Representatives of the tyrosine kinase inhibitor family called tyrphostins, structurally related to known 5-LO inhibitors, were screened for their 5-LO inhibitory properties using recombinant human 5-LO, intact human PMNL (polymorphonuclear leukocytes), and PMNL homogenates. Their mode of action was characterized by the addition of glutathione, using a fourfold cysteine 5-LO mutant and mass spectrometry analysis. SAR studies revealed several members of the tyrphostin family containing a Michael-reactive cyanoacrylate to efficiently inhibit 5-LO. We identified degrasyn (IC50 0.11 µM), tyrphostin A9 (IC50 0.8 µM), AG879 (IC50 78 nM), and AG556 (IC50 64 nM) as potent 5-LO inhibitors. Mass spectrometry analysis revealed that degrasyn and AG556 covalently bound to up to four cysteines, including C416 and/or C418 which surround the substrate entry site. Furthermore, the 5-LO inhibitory effect of degrasyn was remarkably impaired by the addition of glutathione or by the mutation of cysteines to serines at the surface of 5-LO. We successfully identified several tyrphostins as potent inhibitors of human 5-LO. Degrasyn and AG556 were able to covalently bind to 5-LO via their cyanoacrylate moiety. This provides a promising mechanism for targeting 5-LO by Michael acceptors, leading to new therapeutic opportunities in the field of inflammation and cancer.

Anticancer and Antibacterial Activeness of Fused Pyrimidines: Newfangled Updates

Pyrimidine-based heterocyclic compounds are garnering substantial interest due to their essential role as a class of natural and synthetic molecules. These compounds show a diverse array of biologically relevant activities, making them highly prospective candidates for clinical translation as therapeutic agents in combating various diseases. Pyrimidine derivatives and their fused analogues, such as thienopyrimidines, pyrazolopyrimidines, pyridopyrimidines, and pyrimidopyrimidines, hold immense possibility in both anticancer and antibacterial research. These compounds exhibit notable efficacy by targeting protein kinases, which are crucial enzymes regulating fundamental cellular processes like metabolism, migration, division, and growth. Through enzyme inhibition, these derivatives disrupt key cellular signaling pathways, thereby affecting critical cellular functions and viability. The advantage lies in the ubiquity of the pyrimidine structure across various natural compounds, enabling interactions with enzymes, genetic material, and cellular components pivotal for chemical and biological processes. This interaction plays a central role in modulating vital biological activities, making pyrimidine-containing compounds indispensable in drug discovery. In the realm of anticancer therapy, these compounds strategically target key proteins like EGFR, important for aberrant cell growth. Fused pyrimidine motifs, exemplified by various drugs, are designed to inhibit EGFR, thereby impeding tumor progression. Moreover, these compounds influence potent antibacterial activity, interfering with microbial growth through mechanisms ranging from DNA replication inhibition to other vital cellular functions. This dual activity, targeting both cancer cells and microbial pathogens, underscores the versatility and potential of pyrimidine derivatives in medical applications. This review provides insights into the structural characteristics, synthesis methods, and significant medicinal applications of fused pyrimidine derivatives, highlighting their double role in combating cancer and bacterial infections.

Hyperthermia in Combination with Emerging Targeted and Immunotherapies as a New Approach in Cancer Treatment

Despite significant advancements in the development of novel therapies, cancer continues to stand as a prominent global cause of death. In many cases, the cornerstone of standard-of-care therapy consists of chemotherapy (CT), radiotherapy (RT), or a combination of both. Notably, hyperthermia (HT), which has been in clinical use in the last four decades, has proven to enhance the effectiveness of CT and RT, owing to its recognized potency as a sensitizer. Furthermore, HT exerts effects on all steps of the cancer-immunity cycle and exerts a significant impact on key oncogenic pathways. Most recently, there has been a noticeable expansion of cancer research related to treatment options involving immunotherapy (IT) and targeted therapy (TT), a trend also visible in the research and development pipelines of pharmaceutical companies. However, the potential results arising from the combination of these innovative therapeutic approaches with HT remain largely unexplored. Therefore, this review aims to explore the oncology pipelines of major pharmaceutical companies, with the primary objective of identifying the principal targets of forthcoming therapies that have the potential to be advantageous for patients by specifically targeting molecular pathways involved in HT. The ultimate goal of this review is to pave the way for future research initiatives and clinical trials that harness the synergy between emerging IT and TT medications when used in conjunction with HT.

Nitrogen-Enriched Biguanidine-Functionalized Cobalt Ferrite Nanoparticles as a Heterogeneous Base Catalyst for Knoevenagel Condensation under Solvent-Free Conditions

Designing efficient, economical heterogeneous catalysts for the Knoevenagel condensation reaction is highly significant owing to the importance of reaction products in industries as well as pharmaceutics. Herein, we have designed and synthesized biguanidine-functionalized basic magnetically retrievable cobalt ferrite nanoparticles (CFNPs) for the synthesis of Knoevenagel condensation products using benzaldehydes and active methylene compounds (malononitrile/ethyl cyanoacetate/cyanoacetamide). Several advanced techniques, such as Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibration sample magnetometry (VSM), were utilized to precisely characterize the catalyst. The robust features of the current approach involve outstanding catalytic performance, solvent-free reaction conditions, ease of catalyst retrievability, easy workup procedure, large substrate tolerance, high turnover frequency (TOF) values (up to 486.88 h-1), values of green chemistry metrics such as E-factor (0.15), reaction mass efficiency (RME) value (87.07%), carbon efficiency (93.4%), and atom economy (AE) value (88.10%) close to their ideal values, and recyclability up to eight runs without a considerable reduction in activity, boosting the appeal of this approach from a commercial and ecological point of view.

Elucidating the molecular mechanisms of ozone therapy for neuropathic pain management by integrated transcriptomic and metabolomic approach

Introduction: Neuropathic pain remains a prevalent and challenging condition to treat, with current therapies often providing inadequate relief. Ozone therapy has emerged as a promising treatment option; however, its mechanisms of action in neuropathic pain remain poorly understood. Methods: In this study, we investigated the effects of ozone treatment on gene expression and metabolite levels in the brainstem and hypothalamus of a rat model, using a combined transcriptomic and metabolomic approach. Results: Our findings revealed significant alterations in key genes, including DCST1 and AIF1L, and metabolites such as Aconitic acid, L-Glutamic acid, UDP-glucose, and Tyrosine. These changes suggest a complex interplay of molecular pathways and region-specific mechanisms underlying the analgesic effects of ozone therapy. Discussion: Our study provides insights into the molecular targets of ozone treatment for neuropathic pain, laying the groundwork for future research on validating these targets and developing novel therapeutic strategies.

Development and Applications of Chimera Platforms for Tyrosine Phosphorylation

Chimeric small molecules that induce post-translational modification (PTM) on a target protein by bringing it into proximity to a PTM-inducing enzyme are furnishing novel modalities to perturb protein function. Despite recent advances, such molecules are unavailable for a critical PTM, tyrosine phosphorylation. Furthermore, the contemporary design paradigm of chimeric molecules, formed by joining a noninhibitory binder of the PTM-inducing enzyme with the binder of the target protein, prohibits the recruitment of most PTM-inducing enzymes as their noninhibitory binders are unavailable. Here, we report two platforms to generate phosphorylation-inducing chimeric small molecules (PHICS) for tyrosine phosphorylation. We generate PHICS from both noninhibitory binders (scantily available, platform 1) and kinase inhibitors (abundantly available, platform 2) using cysteine-based group transfer chemistry. PHICS triggered phosphorylation on tyrosine residues in diverse sequence contexts and target proteins (e.g., membrane-associated, cytosolic) and displayed multiple bioactivities, including the initiation of a growth receptor signaling cascade and the death of drug-resistant cancer cells. These studies provide an approach to induce biologically relevant PTM and lay the foundation for pharmacologic PTM editing (i.e., induction or removal) of target proteins using abundantly available inhibitors of PTM-inducing or -erasing enzymes.

Synthesis of New Derivatives of Benzylidinemalononitrile and Ethyl 2-Cyano-3-phenylacrylate: In Silico Anticancer Evaluation

In this study, microwave-assisted Knoevenagel condensation was used to produce two novel series of derivatives (1-6) from benzylidenemalononitrile and ethyl 2-cyano-3-phenylacrylate. The synthesized compounds were characterized using Fourier transform infrared (FT-IR) and ¹H NMR spectroscopies. The pharmacodynamics, toxicity profiles, and biological activities of the compounds were evaluated through an in silico study using prediction of activity spectra for substances (PASS) and Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) studies. According to the PASS prediction results, compounds 1-6 showed greater antineoplastic potency for breast cancer than other types of cancer. Molecular docking was employed to investigate the binding mode and interaction sites of the derivatives (1-6) with three human cancer targets (HER2, EGFR, and human FPPS), and the protein-ligand interactions of these derivatives were compared to those reference standards Tyrphostin 1 (AG9) and Tyrphostin 23 (A23). Compound 3 showed a stronger effect on two cell lines (HER2 and FPPS) than the reference drugs. A 20 ns molecular dynamics (MD) simulation was also conducted to examine the ligand's behavior at the active binding site of the modeled protein, utilizing the lowest docking energy obtained from the molecular docking study. Enthalpies (ΔH), Gibbs free energies (ΔG), entropies (ΔS), and frontier molecular orbital parameters (highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap, hardness, and softness) were calculated to confirm the thermodynamic stability of all derivatives. The consistent results obtained from the in silico studies suggest that compound 3 has potential as a new anticancer and antiparasitic drug. Further research is required to validate its efficacy.

Enzymatic Phosphorylation of Oxidized Tyrosine Residues

Post-translational modifications (PTMs) alter the function and fate of proteins and cells in almost every conceivable way. Protein modifications can occur as a result of specific regulating actions of enzymes, such as tyrosine kinases phosphorylating tyrosine residues or by nonenzymatic reactions, such as oxidation related to oxidative stress and diseases. While many studies have addressed the multisite, dynamic, and network-like properties of PTMs, only little is known of the interplay of the same site modifications. In this work, we studied the enzymatic phosphorylation of oxidized tyrosine (l-DOPA) residues using synthetic insulin receptor peptides, in which tyrosine residues were replaced with l-DOPA. The phosphorylated peptides were identified by liquid chromatography-high-resolution mass spectrometry and the site of phosphorylation by tandem mass spectrometry. The results clearly show that the oxidized tyrosine residues are phosphorylated, displaying a specific immonium ion peak in the MS² spectra. Furthermore, we detected this modification in our reanalysis (MassIVE ID: MSV000090106) of published bottom-up phosphoproteomics data. The modification, where both oxidation and phosphorylation take place at the same amino acid, has not yet been published in PTM databases. Our data indicate that there can be multiple PTMs that do not exclude each other at the same modification site.

A Review on Fused Pyrimidine Systems as EGFR Inhibitors and Their Structure–Activity Relationship

Epidermal growth factor receptor (EGFR) belongs to the family of tyrosine kinase that is activated when a specific ligand binds to it. The EGFR plays a vital role in the cellular proliferation process, differentiation, and apoptosis. In the case of cancer, EGFR undergoes uncontrolled auto-phosphorylation that results in increased cellular proliferation and decreased apoptosis, causing cancer promotion. From the literature, it shows that pyrimidine is one of the most commonly studied heterocycles for its antiproliferative activity against EGFR inhibition. The authors have collated some interesting results in the heterocycle-fused pyrimidines that have been studied using different cell lines (sensitive and mutational) and in animal models to determine their activity and potency. It is quite clear that the fused systems are highly effective in inhibiting EGFR activity in cancer cells. Therefore, the structure–activity relationship (SAR) comes into play in determining the nature of the heterocycle and the substituents that are responsible for the increased activity and toxicity. Understanding the SAR of heterocycle-fused pyrimidines will help in getting a better overview of the molecules concerning their activity and potency profile as future EGFR inhibitors.

Vascular Endothelial Growth Factor Receptors [VEGFR] as Target in Breast Cancer Treatment: Current Status in Preclinical and Clinical Studies and Future Directions

Breast cancer [BC] is one of the most common cancers among women, one of the leading causes of a considerable number of cancer-related death globally. Among all procedures leading to the formation of breast tumors, angiogenesis has an important role in cancer progression and outcomes. Therefore, various anti-angiogenic strategies have developed so far to enhance treatment's efficacy in different types of BC. Vascular endothelial growth factors [VEGFs] and their receptors are regarded as the most well-known regulators of neovascularization. VEGF binding to vascular endothelial growth factor receptors [VEGFRs] provides cell proliferation and vascular tissue formation by the subsequent tyrosine kinase pathway. VEGF/VEGFR axis displays an attractive target for anti-angiogenesis and anti-cancer drug design. This review aims to describe the existing literature regarding VEGFR inhibitors, focusing on BC treatment reported in the last two decades.

Drug Repurposing and De Novo Drug Discovery of Protein Kinase Inhibitors as New Drugs against Schistosomiasis

Schistosomiasis is a neglected tropical disease affecting more than 200 million people worldwide. Chemotherapy relies on one single drug, praziquantel, which is safe but ineffective at killing larval stages of this parasite. Furthermore, concerns have been expressed about the rise in resistance against this drug. In the absence of an antischistosomal vaccine, it is, therefore, necessary to develop new drugs against the different species of schistosomes. Protein kinases are important molecules involved in key cellular processes such as signaling, growth, and differentiation. The kinome of schistosomes has been studied and the suitability of schistosomal protein kinases as targets demonstrated by RNA interference studies. Although protein kinase inhibitors are mostly used in cancer therapy, e.g., for the treatment of chronic myeloid leukemia or melanoma, they are now being increasingly explored for the treatment of non-oncological conditions, including schistosomiasis. Here, we discuss the various approaches including screening of natural and synthetic compounds, de novo drug development, and drug repurposing in the context of the search for protein kinase inhibitors against schistosomiasis. We discuss the status quo of the development of kinase inhibitors against schistosomal serine/threonine kinases such as polo-like kinases (PLKs) and mitogen-activated protein kinases (MAP kinases), as well as protein tyrosine kinases (PTKs).

Phosphorylation of TRIP13 at Y56 induces radiation resistance but sensitizes head and neck cancer to cetuximab

Radiation therapy, a mainstay of treatment for head and neck cancer, is not always curative due to the development of treatment resistance; additionally, multi-institutional trials have questioned the efficacy of concurrent radiation with cetuximab, the epidermal growth factor receptor (EGFR) inhibitor. We unraveled a mechanism for radiation resistance; that is, radiation induces EGFR, which phosphorylates TRIP13 (thyroid hormone receptor interactor 13) on tyrosine 56. Phosphorylated (phospho-)TRIP13 promotes non-homologous end joining (NHEJ) repair to induce radiation resistance. NHEJ is the main repair pathway for radiation-induced DNA damage. Tumors expressing high TRIP13 do not respond to radiation but are sensitive to cetuximab or cetuximab combined with radiation. Suppression of phosphorylation of TRIP13 at Y56 abrogates these effects. These findings show that EGFR-mediated phosphorylation of TRIP13 at Y56 is a vital mechanism of radiation resistance. Notably, TRIP13-pY56 could be used to predict the response to radiation or cetuximab and could be explored as an actionable target.

Exporting Metal-Carbene Chemistry to Live Mammalian Cells: Copper-Catalyzed Intracellular Synthesis of Quinoxalines Enabled by N-H Carbene Insertions

Implementing catalytic organometallic transformations in living settings can offer unprecedented opportunities in chemical biology and medicine. Unfortunately, the number of biocompatible reactions so far discovered is very limited, and essentially restricted to uncaging processes. Here, we demonstrate the viability of performing metal carbene transfer reactions in live mammalian cells. In particular, we show that copper (II) catalysts can promote the intracellular annulation of alpha-keto diazocarbenes with ortho-amino arylamines, in a process that is initiated by an N-H carbene insertion. The potential of this transformation is underscored by the in cellulo synthesis of a product that alters mitochondrial functions, and by demonstrating cell selective biological responses using targeted copper catalysts. Considering the wide reactivity spectrum of metal carbenes, this work opens the door to significantly expanding the repertoire of life-compatible abiotic reactions.

In Vitro Ubiquitination Platform Identifies Methyl Ellipticiniums as Ubiquitin Ligase Inhibitors

The transfer of the small protein ubiquitin to a target protein is an intricately orchestrated process called ubiquitination that results in modulation of protein function or stability. Proper regulation of ubiquitination is essential, and dysregulation of this process is implicated in several human diseases. An example of a ubiquitination cascade that is a central signaling node in important disease-associated pathways is that of CBLB [a human homolog of a viral oncogene Casitas B-lineage lymphoma (CBL) from the Cas NS-1 murine retrovirus], a RING finger ubiquitin ligase (E3) whose substrates include a number of important cell-signaling kinases. These include kinases important in immune function that act in the T cell receptor and costimulatory pathways, the Tyro/Axl/MerTK (TAM) receptor family in natural killer (NK) cells, as well as growth factor receptor kinases like epidermal growth factor receptor (EGFR). Loss of CBLB has been shown to increase innate and adaptive antitumor immunity. This suggests that small-molecule modulation of CBLB E3 activity could enhance antitumor immunity in patients. To explore the hypothesis that enzymatic inhibition of E3s may result in modulation of disease-related signaling pathways, we established a high-throughput screen of >70,000 chemical entities for inhibition of CBLB activity. Although CBLB was chosen as a proof-of-principle target for inhibitor discovery, we demonstrate that our assay is generalizable to monitoring the activity of other ubiquitin ligases. We further extended our observed in vitro inhibition with additional cell-based models of CBLB activity. From these studies, we demonstrate that a class of natural product-based alkaloids, known as methyl ellipticiniums (MEs), is capable of inhibiting ubiquitin ligases intracellularly.

Targeting the Fibroblast Growth Factor Receptor (FGFR) Family in Lung Cancer

Lung cancer is the most common cause of cancer-related deaths globally. Genetic alterations, such as amplifications, mutations and translocations in the fibroblast growth factor receptor (FGFR) family have been found in non-small cell lung cancer (NSCLC) where they have a role in cancer initiation and progression. FGFR aberrations have also been identified as key compensatory bypass mechanisms of resistance to targeted therapy against mutant epidermal growth factor receptor (EGFR) and mutant Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) in lung cancer. Targeting FGFR is, therefore, of clinical relevance for this cancer type, and several selective and nonselective FGFR inhibitors have been developed in recent years. Despite promising preclinical data, clinical trials have largely shown low efficacy of these agents in lung cancer patients with FGFR alterations. Preclinical studies have highlighted the emergence of multiple intrinsic and acquired resistance mechanisms to FGFR tyrosine kinase inhibitors, which include on-target FGFR gatekeeper mutations and activation of bypass signalling pathways and alternative receptor tyrosine kinases. Here, we review the landscape of FGFR aberrations in lung cancer and the array of targeted therapies under clinical evaluation. We also discuss the current understanding of the mechanisms of resistance to FGFR-targeting compounds and therapeutic strategies to circumvent resistance. Finally, we highlight our perspectives on the development of new biomarkers for stratification and prediction of FGFR inhibitor response to enable personalisation of treatment in patients with lung cancer.

Binding of tyrosine kinase inhibitor to epidermal growth factor receptor: surface-enhanced infrared absorption microscopy reveals subtle protein secondary structure variations

Surface-Enhanced Infrared Absorption (SEIRA) has been proposed as a valuable tool for protein binding studies, but its performances have been often proven on model proteins undergoing severe secondary structure rearrangements, while ligand binding only marginally involves the protein backbone in the vast majority of the biologically relevant cases. In this study we demonstrate the potential of SEIRA microscopy for highlighting the very subtle secondary structure modifications associated with the binding of Lapatinib, a tyrosine kinase inhibitor (TKI), to epidermal growth factor receptor (EGFR), a well-known driver of tumorigenesis in pathological settings such as lung, breast and brain cancers. By boosting the performances of Mid-IR plasmonic devices based on nanoantennas cross-geometry, accustoming the protein purification protocols, carefully tuning the protein anchoring methodology and optimizing the data analysis, we were able to detect EGFR secondary structure modification associated with few amino acids. A nano-patterned platform with this kind of sensitivity bridges biophysical and structural characterization methods, thus opening new possibilities in studying of proteins of biomedical interest, particularly for drug-screening purposes.

Anti-VEGF DNA-based aptamers in cancer therapeutics and diagnostics

The vascular endothelial growth factor (VEGF) family and its receptors play fundamental roles not only in physiological but also in pathological angiogenesis, characteristic of cancer progression. Aiming at finding putative treatments for several malignancies, various small molecules, antibodies, or protein-based drugs have been evaluated in vitro and in vivo as VEGF inhibitors, providing efficient agents approved for clinical use. Due to the high clinical importance of VEGF, also a great number of anti-VEGF nucleic acid-based aptamers-that is, oligonucleotides able to bind with high affinity and specificity a selected biological target-have been developed as promising agents in anticancer strategies. Notable research efforts have been made in optimization processes of the identified aptamers, searching for increased target affinity and/or bioactivity by exploring structural analogues of the lead compounds. This review is focused on recent studies devoted to the development of DNA-based aptamers designed to target VEGF. Their therapeutic potential as well as their significance in the construction of highly selective biosensors is here discussed.

Synthesis of benzylidenemalononitrile by Knoevenagel condensation through monodisperse carbon nanotube-based NiCu nanohybrids

Monodisperse nickel/copper nanohybrids (NiCu@MWCNT) based on multi-walled carbon nanotubes (MWCNT) were prepared for the Knoevenagel condensation of aryl and aliphatic aldehydes. The synthesis of these nanohybrids was carried out by the ultrasonic hydroxide assisted reduction method. NiCu@MWCNT nanohybrids were characterized by analytical techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. According to characterization results, NiCu@MWCNT showed that these nanohybrids form highly uniform, crystalline, monodisperse, colloidally stable NiCu@MWCNT nanohybrids were successfully synthesized. Thereafter, a model reaction was carried out to obtain benzylidenemalononitrile derivatives using NiCu@MWCNT as a catalyst, and showed high catalytic performance under mild conditions over 10-180 min.

Characterization of Atypical Protein Tyrosine Kinase (PTK) Genes and Their Role in Abiotic Stress Response in Rice

Tyrosine phosphorylation constitutes up to 5% of the total phophoproteome. However, only limited studies are available on protein tyrosine kinases (PTKs) that catalyze protein tyrosine phosphorylation in plants. In this study, domain analysis of the 27 annotated PTK genes in rice genome led to the identification of 18 PTKs with tyrosine kinase domain. The kinase domain of rice PTKs shared high homology with that of dual specificity kinase BRASSINOSTEROID-INSENSITIVE 1 (BRI1) of Arabidopsis. In phylogenetic analysis, rice PTKs clustered with receptor-like cytoplasmic kinases-VII (RLCKs-VII) of Arabidopsis. mRNAseq analysis using Genevestigator revealed that rice PTKs except PTK9 and PTK16 express at moderate to high level in most tissues. PTK16 expression was highly abundant in panicle at flowering stage. mRNAseq data analysis led to the identification of drought, heat, salt, and submergence stress regulated PTK genes in rice. PTK14 was upregulated under all stresses. qRT-PCR analysis also showed that all PTKs except PTK10 were significantly upregulated in root under osmotic stress. Tissue specificity and abiotic stress mediated differential regulation of PTKs suggest their potential role in development and stress response of rice. The candidate dual specificity PTKs identified in this study paves way for molecular analysis of tyrosine phosphorylation in rice.

EGFRvIII: An Oncogene with Ambiguous Role

Epidermal growth factor receptor variant III (EGFRvIII) seems to constitute the perfect therapeutic target for glioblastoma (GB), as it is specifically present on up to 28-30% of GB cells. In case of other tumor types, expression and possible role of this oncogene still remain controversial. In spite of EGFRvIII mechanism of action being crucial for the design of small active anticancer molecules and immunotherapies, i.e., CAR-T technology, it is yet to be precisely defined. EGFRvIII is known to be resistant to degradation, but it is still unclear whether it heterodimerizes with EGF-activated wild-type EGFR (EGFRWT) or homodimerizes (including covalent homodimerization). Constitutive kinase activity of this mutated receptor is relatively low, and some researchers even claim that a nuclear, but not a membrane function, is crucial for its activity. Based on the analyses of recurrent tumors that are often lacking EGFRvIII expression despite its initial presence in corresponding primary foci, this oncogene is suggested to play a marginal role during later stages of carcinogenesis, while even in primary tumors EGFRvIII expression is detected only in a small percentage of tumor cells, undermining the rationality of EGFRvIII-targeting therapies. On the other hand, EGFRvIII-positive cells are resistant to apoptosis, more invasive, and characterized with enhanced proliferation rate. Moreover, expression of this oncogenic receptor was also postulated to be a marker of cancer stem cells. Opinions regarding the role that EGFRvIII plays in tumorigenesis and for tumor aggressiveness are clearly contradictory and, therefore, it is crucial not only to determine its mechanism of action, but also to unambiguously define its role at early and advanced cancer stages.

Nanoformulations of small molecule protein tyrosine kinases inhibitors potentiate targeted cancer therapy

Protein tyrosine kinases (PTKs) are closely related to tumor development and usually participate in apoptosis, DNA repair, and cell proliferation by activating signaling pathways. Therefore, PTKs have become the most promising targets for cancer therapy. In recent years, a large number of studies on the mechanism of tyrosine kinase activation have indicated that tyrosine kinase inhibitors (TKIs) have important clinical significance and application prospects as targeted anticancer drugs because they can effectively block certain cellular signaling pathways, inhibit tumor metastases and reduce tumor proliferation. Although the increasing emergence of anticancer drug resistance limits the clinical application of TKIs, emerging nanotechnology has made it possible to solve this problem. In this work, the state-of-art of small molecule protein tyrosine kinase inhibitors and the applications of drug delivery systems for TKIs are reviewed, and the potentials and challenges for future research of small molecule TKIs are addressed.

Preconditioning hippocampal slices with hypothermia promotes rapid tolerance to hypoxic depolarization and swelling: Mediation by erythropoietin

We suggested previously that hippocampal slices were protected from hypoxic depolarization and swelling by preincubating them at room temperature (Kreisman et al., 2000). We postulated that hypothermic preconditioning induced tolerance in our slices, which protected against hypoxic depolarization and swelling. Control hippocampal slices were incubated at 34-35 °C for two hours and the response to 10 min of severe hypoxia was compared to slices which were preconditioned for two hours at room temperature (22-23 °C) prior to warming to 34-35 °C. Recordings of the extracellular DC potential provided an index of tissue depolarization and changes in tissue light transmittance provided an index of swelling. Hypothermic preconditioning significantly reduced hypoxia-induced swelling, particularly in CA3 and the dentate inner blade. Since erythropoietin (EPO) had been shown to mediate hypoxic preconditioning, we tested whether EPO also mediated hypothermic preconditioning in our slices. Recombinant rat EPO (1-10 micromolar) mitigated hypoxia-induced swelling and depolarization in dentate inner blade of unconditioned slices in a dose-dependent manner. We also blocked the protective effects of hypothermic preconditioning on hypoxic depolarization and swelling in the inner blade of the dentate gyrus by administering soluble EPO receptor in the bath and treating slices with wortmannin to block phosphorylation of PI3 kinase, a critical step in the activation of the downstream neuroprotectant, Akt. These results suggest that EPO mediates tolerance to hypoxic depolarization and swelling induced by hypothermic preconditioning. They also emphasize that various preincubation protocols used in experiments with hippocampal slices may differentially affect basal electrophysiological and metabolic properties of those slices.

Exploring the interaction between tyrphostin 9 and human serum albumin using biophysical and computational methods

Tyrphostin 9 (Tyr 9) is a potent platelet-derived growth factor receptor (PDGFR) inhibitor, which induces apoptosis in various cancer cell types. The binding of Tyr 9 to the major transport protein, human serum albumin (HSA) was investigated using several spectroscopic techniques and molecular docking method. Fluorescence quenching titration results showed progressive decrease in the protein fluorescence with increasing drug concentrations. A decreasing trend of the Stern-Volmer constant, K _sv with increasing temperature characterized the drug-induced quenching as static quenching, thus pointed towards the formation of Tyr 9-HSA complex. The binding constant of Tyr 9-HSA interaction was found to lie within the range 3.48-1.69 × 10⁵ M^-1 at three different temperatures, i.e. 15 °C, 25 °C and 35 °C, respectively and suggested intermediate binding affinity between Tyr 9 and HSA. The drug-HSA complex seems to be stabilized by hydrophobic forces, van der Waals forces and hydrogen bonds, as suggested from the thermodynamic data as well as molecular docking results. The far-UV and the near-UV CD spectral results showed slight alteration in the secondary and tertiary structures, respectively, of the protein upon Tyr 9 binding. Interaction of Tyr 9 with HSA also produced microenvironmental perturbations around protein fluorophores, as evident from the three-dimensional fluorescence spectral results but increased protein's thermal stability. Both competitive drug binding results and molecular docking analysis suggested Sudlow's Site I of HSA as the preferred Tyr 9 binding site. Communicated by Ramaswamy H. Sarma.

Marine anticancer drugs and their relevant targets: a treasure from the ocean

Marine organisms comprising animals and plants are wealthiest sources of bioactive compounds possessing various pharmacological properties specifically: free radical scavenging, antitumor, antimicrobial, analgesic, neuroprotective and immunomodulatory. Marine drugs provide an alternative source to meet the demand of effective, safe and low-cost drugs that are rising with the continuously growing world population. Cancer is one of the leading reasons of mortality in western nations in contrast to communicable diseases of developing nations. In spite of outstanding developments in cancer therapy in past three decades, there is still an insistent necessity for innovative drugs in the area of cancer biology, especially in the unexplored area of marine anticancer compounds. However, recent technological innovations in structure revelation, synthetic creation of new compounds and biological assays have made possible the isolation and clinical assessment of innumerable unique anticancer compounds from marine environment. This review provides an insight into the anticancer research so far conducted in the area of the marine natural products/synthetic derivatives, their possible molecular targets and the current challenges in the drug development. Graphical abstract.

My journey from tyrosine phosphorylation inhibitors to targeted immune therapy as strategies to combat cancer

Since the 1980s there has been a drive toward personalized targeted therapy for cancer. "Targeted cancer therapy" originally focused on inhibiting essential tumor survival factors, primarily protein tyrosine kinases. The complexity and rapid mutability of tumors, however, enable them to develop resistance to tyrosine kinase inhibitors (TKIs), even when these are multitargeted or applied in combination. This has led to the development of targeted cancer immunotherapy, to enhance immune surveillance against the tumor. In this paper, we provide a personal view of the development of targeted therapy, from TKIs to targeted immunotherapy.

Effect of Adherence on Pharmacokinetic/Pharmacodynamic Relationships of Oral Targeted Anticancer Drugs

The emergence of oral targeted anticancer agents transformed several cancers into chronic conditions with a need for long-term oral treatment. Although cancer is a life-threatening condition, oncology medication adherence-the extent to which a patient follows the drug regimen that is intended by the prescriber-can be suboptimal in the long term, as in any other chronic disease. Poor adherence can impact negatively on clinical outcomes, notably because most of these drugs are given as a standard non-individualized dosage despite marked inter-individual variabilities that can lead to toxic or inefficacious drug concentrations. This has been especially studied with the prototypal drug imatinib. In the context of therapeutic drug monitoring (TDM), increasingly advocated for oral anticancer treatment optimization, unreported suboptimal adherence affecting drug intake history may lead to significant bias in the concentration interpretation and inappropriate dosage adjustments. In the same way, suboptimal adherence may also bias the results of pharmacokinetic modeling studies, which will affect in turn Bayesian TDM interpretation that relies on such population models. Detailed knowledge of the influence of adherence on plasma concentrations in pharmacokinetic studies or in routine TDM programs is however presently missing in the oncology field. Studies on this topic are therefore eagerly awaited to better pilot the treatment of cancer with the new targeted agents and to find their optimal dosage regimen. Hence, the development and assessment of effective medication adherence programs are warranted for these treatments.

Investigation of Adsorption Tyrphostin AG528 Anticancer Drug Upon the CNT(6,6-6) Nanotube: A DFT Study

OBJECTIVE

In the present study, the interaction between drug Tyrphostin AG528 and CNT(6,6-6) nanotube by Density Functional Theory (DFT) calculations in solvent water has been investigated for the first time.

METHODS AND RESULTS

According to the calculations, intermolecular hydrogen bonds take place between an active position of the molecule Tyrphostin AG528 and hydrogen atoms of the nanotube which play an important role in the stability of complex CNT(6,6- 6)/Tyrphostin AG528. The non-bonded interaction effects of the molecule Tyrphostin AG528 with CNT(6,6-6) nanotube on the electronic properties, chemical shift tensors and natural charge have also been detected. The natural bond orbital (NBO) analysis suggested that the molecule Tyrphostin AG528 as an electron donor and the CNT(6,6-6) nanotube play the role of an electron acceptor at the complex CNT(6,6-6)/Tyrphostin AG528.

CONCLUSION

The electronic spectra of the Tyrphostin AG528 drug and complex CNT(6,6-6)/Tyrphostin AG528 in solvent water were calculated by Time-Dependent Density Functional Theory (TD-DFT) for the investigation of adsorption effect of the Tyrphostin AG528 drug over nanotube on maximum wavelength. Then, the possibility of the use of CNT(6,6-6) nanotube for Tyrphostin AG528 delivery to the diseased cells has been established.

Nonconjugated Hydrocarbons as Rigid-Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry

Nonconjugated hydrocarbons, like bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, triptycene, and cubane are a unique class of rigid linkers. Due to their similarity in size and shape they are useful mimics of classic benzene moieties in drugs, so-called bioisosteres. Moreover, they also fulfill an important role in material sciences as linear linkers, in order to arrange various functionalities in a defined spatial manner. In this Review article, recent developments and usages of these special, rectilinear systems are discussed. Furthermore, we focus on covalently linked, nonconjugated linear arrangements and discuss the physical and chemical properties and differences of individual linkers, as well as their application in material and medicinal sciences.

CSF nerve growth factor (β-NGF) is increased but CSF insulin-like growth factor-(IGF-1) is normal in children with tuberous sclerosis and infantile spasms

Tuberous sclerosis is associated with epilepsy that is often refractory. We examined cerebrospinal fluid (CSF) concentrations for neurotrophins, nerve growth factor (β-NGF) and insulin-like growth factor (IGF-1) in children with infantile spasms between 1997 and 2010. We classified the patients as follows: tuberous sclerosis (n = 5), cryptogenic spasms (n = 6), postinfectious spasms (n = 5) and other symptomatic spasms (n = 22). We had 22 age- and sex-matched controls for CSF-NGF and 14 for CSF-IGF-1. The median of CSF-NGF was higher in those with tuberous sclerosis, 56 (minimum-maximum, 8.0-131) ng/L, in relative to age- and sex-matched controls, 6.7 (0.0-22) ng/L, and symptomatic infantile spasms, 0.0 (0.0-4.5) ng/L or cryptogenic cases of infantile spasms, 6.2 (3.9-8.8) ng/L, respectively. CSF-NGF were highest in children with postinfectious aetiology, 408 (89-778) ng/L. CSF-IGF-1 of tuberous sclerosis, 0.65 (0.35-0.98) μg/L, did not differ from the cryptogenic spasms, 0.68 (0.32-0.87) μg/L, or from age- and sex-matched controls 0.52 (0.22-0.77) μg/L. Patients with tuberous sclerosis and cryptogenic spasms had normal development prior the ACTH therapy. We suggest that increased CSF-NGF might indicate a persistent activation of inflammatory pathways in cortical tubers in tuberous sclerosis and this would reflect in CSF concentrations.

Synthesis, anticancer activity, toxicity evaluation and molecular docking studies of novel phenylaminopyrimidine-(thio)urea hybrids as potential kinase inhibitors

Thirty-two novel urea/thiourea compounds as potential kinase inhibitor were designed, synthesized and evaluated for their cytotoxic activity on breast (MCF7), colon (HCT116) and liver (Huh7) cancer cell lines. Compounds 10, 19 and 30 possessing anticancer activity with IC₅₀ values of 0.9, 0.8 and 1.6μM respectively on Huh7 cells were selected for further studies. These hit compounds were tested against liver carcinoma panel. Real time cell electronic sensing assay was used to evaluate the effects of the compounds 10, 19 and 30 on the growth pattern of liver cancer cells. Apoptotic cell death and cell cycle analysis upon treatment of liver carcinoma cells with hit compounds were determined. A significant apoptotic cell death was detected upon treatment of Huh7 and Mahlavu cells with compound 30 after 48 h of treatment. Additionally, compound 10 caused cell cycle arrest at G0/G1 phase. Mutagenicity of hit compounds was evaluated. Assertively, these compounds were not found to be mutagenic on Salmonella typhimurium strains TA98 and TA100. To understand the binding modes of the synthesized compounds, molecular docking studies were performed using the crystal data of VEGFR and Src-kinase enzymes in correlation with anticancer activities.

Prolonging Gastrointestinal-Stromal-Tumor-free life, an optimal suggestion of imatinib intervention ahead of operation

Background: Imatinib has been regarded as the first successful synthetic small molecule targeting at blocking tyrosine kinase. Its high efficacy stabilized disease in above 80% of chronic myeloid leukemia (CML) patients over 10 years survival. Due to the similar canceration of gastrointestinal stromal tumor (GIST) as to CML, imatinib has been approved to be used as first-line treatment. Study design: Our retrospective study was proposed to enroll 191 GIST patients with larger tumor size (≥8 cm) who preoperative accepted imatinib from those with direct operation. Analysis included demographics, cancer specific survival and relationship of their risk factors. Results: Male patients and gastrointestinal (GI) tract location took higher proportion in total cases, detection of KIT mutant took 89.7% among all traceable genetic testing. Patients with preoperative imatinib can achieve higher cancer specific survival (CSS) after both in 1 year and 3 years duration than their counterpart. Tumor size above its threshold of 8 cm would be a hazardous factor for poor prognosis. Conclusion: In conclusion, as for regressing tumor progression and creating operative chance, preoperative imatinib should be considered for the patients with high risk, although the precise duration of this intervention needs further validation.

Distinct phosphorylation sites/clusters in the carboxyl terminus regulate α1D-adrenergic receptor subcellular localization and signaling

The human α_1D-adrenergic receptor is a seven transmembrane-domain protein that mediates many of the physiological actions of adrenaline and noradrenaline and participates in the development of hypertension and benign prostatic hyperplasia. We recently reported that different phosphorylation patterns control α_1D-adrenergic receptor desensitization. However, to our knowledge, there is no data regarding the role(s) of this receptor's specific phosphorylation residues in its subcellular localization and signaling. In order to address this issue, we mutated the identified phosphorylated residues located on the third intracellular loop and carboxyl tail. In this way, we experimentally confirmed α_1D-AR phosphorylation sites and identified, in the carboxyl tail, two groups of residues in close proximity to each other, as well as two individual residues in the proximal (T442) and distal (S543) regions. Our results indicate that phosphorylation of the distal cluster (T507, S515, S516 and S518) favors α_1D-AR localization at the plasma membrane, i. e., substitution of these residues for non-phosphorylatable amino acids results in the intracellular localization of the receptors, whereas phospho-mimetic substitution allows plasma membrane localization. Moreover, we found that T442 phosphorylation is necessary for agonist- and phorbol ester-induced receptor colocalization with β-arrestins. Additionally, we observed that substitution of intracellular loop 3 phosphorylation sites for non-phosphorylatable amino acids resulted in sustained ERK1/2 activation; additional mutations in the phosphorylated residues in the carboxyl tail did not alter this pattern. In contrast, mobilization of intracellular calcium and receptor internalization appear to be controlled by the phosphorylation of both third-intracellular-loop and carboxyl terminus-domain residues. In summary, our data indicate that a) both the phosphorylation sites present in the third intracellular loop and in the carboxyl terminus participate in triggering calcium signaling and in turning-off α_1D-AR-induced ERK activation; b) phosphorylation of the distal cluster appears to play a role in receptor's plasma membrane localization; and c) T442 appears to play a critical role in receptor phosphorylation and receptor-β-arrestin colocalization.

The Importance of Tyrosine Phosphorylation Control of Cellular Signaling Pathways in Respiratory Disease: pY and pY Not

Reversible phosphorylation of proteins on tyrosine residues is an essential signaling mechanism by which diverse cellular processes are closely regulated. The tight temporal and spatial control of the tyrosine phosphorylation status of proteins by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) is critical to cellular homeostasis as well as to adaptations to the external environment. Via regulation of cellular signaling cascades involving other protein kinases and phosphatases, receptors, adaptor proteins, and transcription factors, PTKs and PTPs closely control diverse cellular processes such as proliferation, differentiation, migration, inflammation, and maintenance of cellular barrier function. Given these key regulatory roles, it is not surprising that dysfunction of PTKs and PTPs is important in the pathogenesis of human disease, including many pulmonary diseases. The roles of various PTKs and PTPs in acute lung injury and repair, pulmonary fibrosis, pulmonary vascular disease, and inflammatory airway disease are discussed in this review. It is important to note that although there is overlap among many of these proteins in various disease states, the mechanisms by which they influence the pathogenesis of these conditions differ, suggesting wide-ranging roles for these enzymes and their potential as therapeutic targets.

Epidermal Growth Factor - based adhesion substrates elicit myoblast scattering, proliferation, differentiation and promote satellite cell myogenic activation

The biochemical properties of muscle extracellular matrix are essential for stem cell adhesion, motility, proliferation and myogenic development. Recombinant elastin-like polypeptides are synthetic polypeptides that, besides maintaining some properties of the native protein, can be tailored by fusing bioactive sequences to their C-terminal. Our laboratory synthesized several Human Elastin-Like Polypeptides (HELP) derived from the sequence of human tropoelastin. Here, we developed a novel HELP family member by fusing the elastin-like backbone to the sequence of human Epidermal Growth Factor. We employed this synthetic protein, named HEGF, either alone or in combination with other proteins of the HELP family carrying RGD-integrin binding sites, as adhesion substrate for C2C12 myoblasts and satellite cells primary cultures. Adhesion of myoblasts to HEGF-based substrates induced scattering, decreased adhesion and cytoskeleton assembly; the concomitant presence of the RGD motifs potentiated all these effects. Recombinant substrates induced myoblasts proliferation, differentiation and the development of multinucleated myotubes, thus favoring myoblasts expansion and preserving their myogenic potential. The effects induced by adhesion substrates were inhibited by AG82 (Tyrphostin 25) and herbimycin A, indicating their dependence on the activation of both the EGF receptor and the tyrosine kinase c-src. Finally, HEGF increased the number of muscle stem cells (satellite cells) derived from isolated muscle fibers in culture, thus highlighting its potential as a novel substrate for skeletal muscle regeneration strategies.

Protein Tyrosine Signaling and its Potential Therapeutic Implications in Carcinogenesis

Protein tyrosine phosphorylation is a crucial signaling mechanism that plays a role in epithelial carcinogenesis. Protein tyrosine kinases (PTKs) control various cellular processes including growth, differentiation, metabolism, and motility by activating major signaling pathways including STAT3, AKT, and MAPK. Genetic mutation of PTKs and/or prolonged activation of PTKs and their downstream pathways can lead to the development of epithelial cancer. Therefore, PTKs became an attractive target for cancer prevention. PTK inhibitors are continuously being developed, and they are currently used for the treatment of cancers that show a high expression of PTKs. Protein tyrosine phosphatases (PTPs), the homeostatic counterpart of PTKs, negatively regulate the rate and duration of phosphotyrosine signaling. PTPs initially were considered to be only housekeeping enzymes with low specificity. However, recent studies have demonstrated that PTPs can function as either tumor suppressors or tumor promoters, depending on their target substrates. Together, both PTK and PTP signal transduction pathways are potential therapeutic targets for cancer prevention and treatment.

Synthesis and Evaluation of the Anticancer and Trypanocidal Activities of Boronic Tyrphostins

Molecules containing an (cyanovinyl)arene moiety are known as tyrphostins because of their ability to inhibit proteins from the tyrosine kinase family, an interesting target for the development of anticancer and trypanocidal drugs. In the present work, (E)-(cyanovinyl)benzeneboronic acids were synthesized by Knoevenagel condensations without the use of any catalysts in water through a simple protocol that completely avoided the use of organic solvents in the synthesis and workup process. The in vitro anticancer and trypanocidal activities of the synthesized boronic acids were also evaluated, and it was discovered that the introduction of the boronic acid functionality improved the activity of the boronic tyrphostins. In silico target fishing with the use of a chemogenomic approach suggested that tyrosine-phosphorylation-regulated kinase 1a (DYRK1A) was a potential target for some of the designed compounds.

Phase I safety and pharmacokinetic study of cipatinib, an original dual tyrosine kinase inhibitor

Background

Cipatinib is a novel tyrosine kinase inhibitor against both EGFR and HER2/neu. This phase I trial was conducted to assess the safety, dose‐limiting toxicities (DLTs), and maximum‐tolerated dose of cipatinib in HER2‐positive patients with advanced breast cancer.

Methods

Eligible adults with advanced breast cancer were administered cipatinib 200 mg/day (n = 3) as an initial dose, with escalating dosages of 400 mg (n = 4), 800 mg (n = 2), 1200 mg (n = 3), 1400 mg (n = 3), 1600 mg (n = 3), and 1800 mg (n = 2) in 21 day cycles. DLTs were monitored until the end of cycle 2. Physical examinations, vital signs, blood sampling for hematology, clinical chemistry, and pharmacokinetics were performed throughout the trial.

Results

Of the 26 subjects enrolled, 23 completed the trial. A total of 143 adverse events (AEs) were reported, of which 87 were associated with cipatinib treatment and comprised: neutropenia (38%), hypertriglyceridemia (15%), fatigue (15%), nausea (12%), fever (19%), and myocardial ischemia (19%). Six AEs were graded 3–4 (neutropenia, increases in aspartate aminotransferase, and total bilirubin, fatigue, dizziness and nodal tachycardia), but none of the AEs observed were considered to be DLTs.

Conclusion

This tolerability study revealed that despite a mild toxicity profile, cipatinib was well tolerated up to the anticipated maximum dosage of 1800 mg/m². Further clinical trials are warranted.

Tyrphostin AG17 inhibits adipocyte differentiation in vivo and in vitro

Background

Excessive subcutaneous adiposity in obesity is associated to positive white adipocyte tissue (WAT) differentiation (adipogenesis) and WAT expandability. Here, we hypothesized that supplementation with the insulin inhibitor and mitochondrial uncoupler, Tyrphostin (T-AG17), in vitro and in vivo inhibits adipogenesis and adipocyte hypertrophy.

Methods

We used a 3T3-L1 proadipocyte cell line to identify the potential effect of T-AG17 on adipocyte differentiation and fat accumulation in vitro. We evaluated the safety of T-AG17 and its effects on physiological and molecular metabolic parameters including hormonal profile, glucose levels, adipogenesis and adipocyte hypertrophy in a diet-induced obesity model using C57BL/6 mice.

Results

We found that T-AG17 is effective in preventing adipogenesis and lipid synthesis in the 3T3-L1 cell line, as evidenced by a significant decrease in oil red staining (p < 0.05). In obese C57BL/6 mice, oral administration of T-AG17 (0.175 mg/kg for 2 weeks) lead to decreased fat accumulation and WAT hypertrophy. Further, T-AG17 induced adipocyte apoptosis by activating caspase-3. In the hepatocytes of obese mice, T-AG17 promoted an increase in the size of lipid inclusions, which was accompanied by glycogen accumulation. T-AG17 did not alter serum biochemistry, including glucose, insulin, leptin, free fatty acids, creatinine, and aspartate aminotransferase.

Conclusion

T-AG17 promotes adipocyte apoptosis in vivo and is an effective modulator of adipocyte differentiation and WAT hypertrophy in vitro and in vivo. Therefore, T-AG17 may be useful as a pharmacological obesity treatment.

Ascitic fluid from advanced ovarian cancer patients compromises the activity of receptor tyrosine kinase inhibitors in 3D cell clusters of ovarian cancer cells

Ovarian cancer patients in the advanced stages of the disease show clinical ascites, which is associated with a poor prognosis. There is limited understanding of the effect of ascitic fluid on ovarian cancer cells and their response to anticancer drugs. We investigated the antitumour effects of EGFR/Her-2 (canertinib) and c-Met (PHA665752) inhibitors in a 3D cell model of three ovarian cancer lines. Single and combined inhibitor treatments affected cell growth of OVCAR-5 and SKOV-3 cell lines but not OV-90 cell line. Growth reduction was correlated with the down expression of PCNA, EGFR, HER-2, c-MET, ERK and AKT and their phosphorylation status in cells in growth factor supplemented media. However, these effects were not re-producible in OVCAR-5 and SKOV-3 cell lines when they were exposed to ascitic fluid obtained from three ovarian cancer patients. Serum albumin and protein components in the ascitic fluids may reduce the cellular uptake of the inhibitors.

The GSK3β inhibitor BIS I reverts YAP-dependent EMT signature in PDAC cell lines by decreasing SMADs expression level

The Yes-associated protein, YAP, is a transcriptional co-activator, mediating the Epithelial to Mesenchymal Transition program in pancreatic ductal adenocarcinoma (PDAC). With the aim to identify compounds that can specifically modulate YAP functionality in PDAC cell lines, we performed a small scale, drug-based screening experiment using YAP cell localization as the read-out. We identified erlotinib as an inducer of YAP cytoplasmic localization, an inhibitor of the TEA luciferase reporter system and the expression of the bona fide YAP target gene, Connective Tissue Growth Factor CTGF. On the other hand, BIS I, an inhibitor of PKCδ and GSK3β, caused YAP accumulation into the nucleus. Activation of β-catenin reporter and interfering experiments show that inhibition of the PKCδ/GSK3β pathway triggers YAP nuclear accumulation inducing YAP/TEAD transcriptional response. Inhibition of GSK3β by BIS I reduced the expression levels of SMADs protein and reduced YAP contribution to EMT. Notably, BIS I reduced proliferation, migration and clonogenicity of PDAC cells in vitro, phenocopying YAP genetic down-regulation. As shown by chromatin immunoprecipitation experiments and YAP over-expressing rescue experiments, BIS I reverted YAP-dependent EMT program by modulating the expression of the YAP target genes E-cadherin, vimentin, CTGF and of the newly identified target, CD133. In conclusion, we identified two different molecules, erlotinib and BIS I, modulating YAP functionality although via different mechanisms of action, with the second one specifically inhibiting the YAP-dependent EMT program in PDAC cell lines.

FIKK Kinase, a Ser/Thr Kinase Important to Malaria Parasites, Is Inhibited by Tyrosine Kinase Inhibitors

A relatively high-affinity inhibitor of FIKK kinase from the malaria parasite Plasmodium vivax was identified by in vitro assay of recombinant kinase. The FIKK kinase family is unique to parasitic organisms of the Apicomplexan order and has been shown to be critical in malaria parasites. The recombinant kinase domain was expressed and screened against a small molecule library, revealing a number of tyrosine kinase inhibitors that block FIKK kinase activity. A family of tyrphostins was further investigated, to begin exploring the FIKK kinase pharmacophore. Finally, emodin was identified as a relatively high-affinity FIKK kinase inhibitor, identifying this family of anthraquinones as potential lead compounds for the development of antimalarials targeting the FIKK kinase.

The anthraquinone emodin inhibits the non-exported FIKK kinase from Plasmodium falciparum

The FIKK family of kinases is unique to parasites of the Apicomplexan order, which includes all malaria parasites. Plasmodium falciparum, the most virulent form of human malaria, has a family of 19 FIKK kinases, most of which are exported into the host red blood cell during malaria infection. Here, we confirm that FIKK 8 is a non-exported member of the FIKK kinase family. Through expression and purification of the recombinant kinase domain, we establish that emodin is a relatively high-affinity (IC₅₀=2μM) inhibitor of PfFk8. Closely related anthraquinones do not inhibit PfFk8, suggesting that the particular substitution pattern of emodin is critical to the inhibitory pharmacophore. This first report of a P. falciparum FIKK kinase inhibitor lays the groundwork for developing specific inhibitors of the various members of the FIKK kinase family in order to probe their physiological function.